JoVE Logo

Zaloguj się

Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with the stages of development. Prior to differentiation into liver cells, the cells express genes involved in the cell cycle, DNA replication, and proliferation. Later in development, genes involved in epithelial differentiation and blood coagulation are highly expressed. Once cells differentiate into hepatocytes, the expression of genes involved in liver-specific functions increases, such as those involved in lipid metabolism and cholesterol regulation.

Gene expression can be regulated at many points including transcription, translation, RNA processing and transport, and post-translational modifications. Common methods of regulating expression are factors that bind directly to DNA to regulate the transcription of a particular gene. Gene expression in the liver can be regulated by the transcription factors C/EBPα, C/EBPβ, and Hepatocyte Nuclear Factor-1, among others. Regulation can occur prior to transcription by altering the histones contained in chromatin. These modifications result in either loosening or tightening of the DNA structure, thereby respectively preventing or allowing transcriptional regulators to access the DNA. Different cell types have different covalent modifications and histone variants, which results in the variation in gene accessibility.

Cells are subject to environmental changes and express different genes in response to these extracellular stimuli. Glucose is an important source of energy, and as its concentration in the bloodstream fluctuates, an organism must respond with appropriate changes in gene and protein expression. When blood glucose levels decrease, the pancreas secretes the hormone glucagon. This hormone signals the liver to initiate the production of phosphoenolpyruvate carboxykinase (PEPCK), a protein required to produce glucose from non-carbohydrate precursors. Glucagon induces the transcription of this gene by indirectly stimulating transcription factors C/EBPα and C/EBPβ to bind to the PEPCK promoter. When blood glucose levels are high, the pancreas secretes the hormone insulin; the PEPCK gene has an insulin-responsive sequence that inhibits its transcription.

Tagi

Cell Specific Gene ExpressionMulticellular OrganismDNAStructural DifferencesFunctional DifferencesDifferential Expression Of GenesRNAProteinsUnique FunctionsHepatocytesNeuronsAlcohol DehydrogenaseNeurexinsGene Expression RegulationTranscription FactorsExtracellular Environment

Z rozdziału 10:

article

Now Playing

10.1 : Cell Specific Gene Expression

Gene Expression

13.3K Wyświetleń

article

10.2 : Regulacja ekspresji odbywa się na wielu etapach

Gene Expression

22.0K Wyświetleń

article

10.3 : Sekwencje cis-regulatorowe

Gene Expression

9.6K Wyświetleń

article

10.4 : Kooperacyjne wiązanie regulatorów transkrypcji

Gene Expression

6.2K Wyświetleń

article

10.5 : Prokariotyczne aktywatory i represory transkrypcji

Gene Expression

20.3K Wyświetleń

article

10.6 : Operony

Gene Expression

15.4K Wyświetleń

article

10.7 : Region promotora eukariotycznego

Gene Expression

16.0K Wyświetleń

article

10.8 : Koaktywatory i korepresory

Gene Expression

7.2K Wyświetleń

article

10.9 : Aktywatory transkrypcji eukariotycznej

Gene Expression

10.8K Wyświetleń

article

10.10 : Inhibitory transkrypcji eukariotycznej

Gene Expression

9.7K Wyświetleń

article

10.11 : Kombinatoryczna kontrola genów

Gene Expression

8.2K Wyświetleń

article

10.12 : Indukowane pluripotencjalne komórki macierzyste

Gene Expression

3.4K Wyświetleń

article

10.13 : Główne regulatory transkrypcji

Gene Expression

6.8K Wyświetleń

article

10.14 : Regulacja epigenetyczna

Gene Expression

24.2K Wyświetleń

article

10.15 : Imprinting i dziedziczenie genomu

Gene Expression

32.9K Wyświetleń

JoVE Logo

Prywatność

Warunki Korzystania

Zasady

Badania

Edukacja

O JoVE

Copyright © 2025 MyJoVE Corporation. Wszelkie prawa zastrzeżone